Coronary stent grafts covered by a polytetrafluoroethylene membrane

Clinical Safety and Efficacy of New-Generation Single-Layer Polytetrafluorethylene Covered Coronary Stents

BACKGROUND

Early-generation "sandwich-design" polytetrafluorethylene (PTFE) covered coronary stents (CS) are associated with a high frequency of adverse events. New-generation single layer PTFE-CS offers the potential to enhanced procedural efficacy and improves clinical safety. Data from a dedicated study, concerning outcomes after treatment with single-layer PTFE-CS in patients undergoing percutaneous coronary intervention are scant.

METHODS

This is a retrospective multicenter registry including 30 patients undergoing implantation of 39 single-layer PTFE-CS (BeGraft-coronary Stent Graft System, Bentley InnoMed GmbH, Hechingen, Germany) in native coronary arteries or saphenous bypass grafts, in 3 centers in Europe, between May 2013 and May 2019. Endpoints of interest were procedural success (placement of covered stent), binary-angiographic restenosis (BAR), percent diameter stenosis (% DS) and late-lumen loss at 6-8 months follow-up angiography, rates of target lesion revascularization (TLR), myocardial infarction (MI), stent thrombosis (ST) and mortality at 12 months.

RESULTS

28 patients underwent implantation of 37 CS due to coronary artery perforation 2 patients due to coronary artery aneurysm. Technical success was achieved in all patients (100 %). More than one stent was implanted in 7 patients (25 %) all in the perforation group. Follow-up angiography was available in 23 patients (77 %) showing favorable results: BAR = 21.8 %, %DS = 30.3 ± 27.5; LLL = 0.16 ± 0.81 mm. At 12 months all patients were alive, rates of TLR were low (3 patients, 10.0 %), there was one case of late stent thrombosis (3.3 %) and one MI (3.3 %).

CONCLUSIONS

In this dedicated study, implantation of a new single layer PTFE-CS for the treatment of native coronary arteries or saphenous vein grafts after perforation or due to aneurysm showed high technical success rates and favorable angiographic and clinical efficacy. Clinical safety outcomes are encouraging, but larger prospective studies are needed to determine long-term safety of this device.

Use of the PK Papyrus covered coronary stent in the treatment of Kawasaki disease-associated giant coronary artery aneurysms

Kawasaki disease (KD) is an acute vasculitis that can cause coronary artery inflammation and aneurysm formation leading to early obstructive disease. We describe the use of PK Papyrus covered stents (Biotronic, Inc.) in three pediatric patients to exclude coronary artery aneurysms (CAA) from the circulation and relieve aneurysm associated stenoses. Follow-up angiography at 11-17 months postprocedure demonstrated persistent exclusion of CAA and varying degrees of in-stent restenosis (ISR). Two patients required percutaneous coronary intervention with drug eluting stent (DES) implantation to relieve in-stent stenosis. Our findings suggest that CAA exclusion with the PK Papyrus stent is possible and may be a valuable tool in simultaneously treating stenotic and thrombogenic CAA in pediatric KD patients. ISR of these non-DES remains an issue and may require additional interventions within the short-term to maintain vessel patency.

Clinical Outcomes of Self-Made Polyurethane-Covered Stent Implantation for the Treatment of Coronary Artery Perforations

Objectives

The present study aimed to investigate the short- and long-term clinical outcomes of self-made polyurethane-covered stents (PU-CS) in patients for the management of coronary artery perforation (CAP) during percutaneous coronary intervention (PCI).

Background

Coronary artery perforation is reckoned as a serious complication in PCI and associated with considerable morbidity and mortality. Covered stents have been used for treating the life-threatening CAP during PCI. But in some catheterization laboratories, no commercial CS is immediately available when there is an urgent need for CS to rescue the coronary rupture site.

Methods

We retrospectively identified 24 patients who underwent 31 self-made PU-CS implantations due to CAP in Zhongshan Hospital, Fudan University, from June 2015 to January 2020.

Results

The total procedural success rate of CS to seal the perforation was 79.2%. Nine patients (37.5%) developed cardiac tamponade, of which 8 patients (33.3%) underwent pericardiocentesis and 4 patients (16.7%) underwent cardiac surgeries. Except for 4 cardiac death cases (16.7%), none of myocardial infarction (MI), target lesion revascularization (TLR), and stent thrombosis (ST) was reported during hospital stay. Data from 22 patients (91.7%) were available at 610.4 ± 420.9 days of follow-up. Major adverse cardiac events (MACE) occurred in 6 patients (27.3%), including 5 cases of cardiac death and one TLR case.

Conclusions

Self-made PU-CS demonstrates high rates of successful delivery and sealing of severe CAP during PCI. Although the in-hospital mortality remains high after PU-CS implantation, the long-term follow-up shows favorable clinical outcomes, indicating the feasibility of PU-CS in treating CAP.

Evaluation of Biodegradable Stent Graft Coatings in Pig and Rabbit Models

AIMS

Percutaneous coronary intervention is routinely performed to treat occlusive coronary artery disease. Coronary perforation is a potential complication and can be treated with a stent graft. Current stent grafts are associated with high restenosis rates. We tested the safety and feasibility of biodegradable stent grafts in pig and rabbit models.

METHODS AND RESULTS

Stent grafts were examined in pig coronaries with repeated OCT imaging for 42 days. Novel biodegradable coatings were applied on a bare metal stent by either an electrospinning (ES) or dip coating (DC) method. A completely biodegradable system was made by ES coating a magnesium-based stent. A commercially available stent graft served as a control. ES devices showed less restenosis (44.3 ± 8.8 vs. 59.1 ± 11.1% in controls, p < 0.05) and smaller reduction in minimum lumen area (44.3 ± 13.4 vs. 64.4 ± 13.6% in controls, p < 0.05) at day 42. DC devices occluded during follow-up. ES devices showed recanalization through the graft wall at day 42. Feasibility of the ES and DC devices was evaluated in pig coronary aneurysms and rabbit aortic perforation models and sealed aneurysms and perforations without complications.

CONCLUSIONS

Recanalization of the graft wall improves biocompatibility. Biodegradable stent grafts may present an alternative to permanent implants by showing reduced restenosis at day 42.

Outcome after new generation single-layer polytetrafluoroethylene-covered stent implantation for the treatment of coronary artery perforation

AIMS

Coronary artery perforation (CAP) is a rare but severe complication during percutaneous coronary intervention (PCI). Implantation of covered stents (CS) represents a potentially life-saving treatment. Concerns exist regarding limited efficacy and high stent thrombosis (ST) rates related to early generation CS. The aim of this study was to evaluate angiographic and clinical outcomes of patients with CAP treated with a new generation single-layer polytetrafluoroethylene (PTFE)-CS.

METHODS

Between May 2013 and November 2017, we identified a total of 61 patients who underwent implantation of 71 single layer PTFE-CS after CAP. We analyzed angiographic results at follow up (including binary angiographic restenosis [BAR] and late-lumen-loss [LLL]) and clinical outcomes in hospital and at follow up, including target lesion revascularization (TLR), cardiovascular-, and all-cause mortality, myocardial infarction (MI) and stent thrombosis (ST).

RESULTS

Procedural success was achieved in all but two patients (96.7%). Procedure related MI, occurred in 19 cases (31.1%), in hospital death occurred in five cases (8.2%). At follow-up, TLR occurred in 11 cases (18.0%), two patients (3.3%) died from non-cardiovascular cause, there was no case of MI or ST.

CONCLUSIONS

In this retrospective analysis, implantation of a new generation PTFE-CS, for the treatment of CAP showed high technical success rates. Although, periprocedural MI-and in-hospital-death rates remain not inconsiderable, new generation PTFE-CS showed favorable angiographic and clinical efficacy and high safety profile, especially with regard to thrombotic events.

Clinical Outcomes of Polytetrafluoroethylene-Covered Stents for Coronary Artery Perforation in Elderly Patients Undergoing Percutaneous Coronary Interventions

Background

Coronary artery perforation (CAP) during percutaneous coronary intervention (PCI) is associated with increased mortality. Polytetrafluoroethylene covered stents (CS) are an effective approach to treat CAP, but data regarding elderly patients requiring CS implantation for CAP are limited. The aim of this study is to report clinical data for elderly CAP patients undergoing CS implantation during PCI.

Methods

Nineteen consecutive elderly patients (≥ 65 years) undergoing CS implantation due to PCI-induced CAP in a tertiary referral center from July 2003 to April 2016 were retrospectively examined.

Results

There were 13 men and six women, with a mean age of 75.3 ± 5.6 years (range: 65-86 years). Perforation grade was Ellis type II in five patients (26.3%), and Ellis type III in 14 patients (73.7%). Cardiac tamponade developed in six patients (31.6%), and intra-aortic balloon pumping was needed in four patients (21.1%). The overall success rate for CS implantation rate was 94.7%. The overall in-hospital mortality rate was 15.8%; the in-hospital myocardial infarction rate was 63.2%. Among 16 survival-to-discharge cases, dual antiplatelet therapy (DAPT) was prescribed in 14 cases (87.5%) for a mean duration of 14 months. Overall, there were five angiogram- proven CS failures among 18 patients receiving successful CS implantation. The 1, 2 and 4 years of actuarial freedom from the CS failure were 78%, 65%, and 43% in the angiogram follow-up patients.

Conclusions

CS implantation for CAP is feasible and effective in elderly patients, while CS failure remains a major concern that encourages regular angiographic follow-up in these case.

Coronary covered stents

Covered stents offer an effective bail-out strategy in vessel perforations, are an alternative to surgery for the exclusion of coronary aneurysms, and have a potential role in the treatment of friable embolisation-prone plaques. The aim of this manuscript is to offer an overview of currently available platforms and to report results obtained in prior studies.

Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents

Stent-grafts are widely used for the treatment of various conditions such as aortic lesions, aneurysms, emboli due to coronary intervention procedures and perforations in vasculature. Such stent-grafts are manufactured by covering a stent with a polymer membrane. An ideal stent-graft should have a biocompatible stent covered by a porous, thromboresistant, and biocompatible polymer membrane which mimics the extracellular matrix thereby promoting injury site healing. The goal of this protocol is to manufacture a small caliber stent-graft by encapsulating a balloon expandable stent within two layers of electrospun polyurethane nanofibers. Electrospinning of polyurethane has been shown to assist in healing by mimicking native extracellular matrix, thereby promoting endothelialization. Electrospinning polyurethane nanofibers on a slowly rotating mandrel enabled us to precisely control the thickness of the nanofibrous membrane, which is essential to achieve a small caliber balloon expandable stent-graft. Mechanical validation by crimping and expansion of the stent-graft has shown that the nanofibrous polyurethane membrane is sufficiently flexible to crimp and expand while staying patent without showing any signs of tearing or delamination. Furthermore, stent-grafts fabricated using the methods described here are capable of being implanted using a coronary intervention procedure using standard size guide catheters.

Short-Term and Long-Term Outcomes After Polytetrafluoroethylene-Covered Stent Implantation for the Treatment of Coronary Perforation

This study sought to evaluate the short-term and 3-year outcomes of polytetrafluoroethylene-covered stent (PCS) for patients with coronary perforation. Implantation of a PCS has improved the immediate clinical outcomes of patients with coronary perforation. However, there are few reports regarding long-term outcomes. We evaluated a total of 57 patients who were treated with PCS for coronary perforation from April 2004 to March 2015 at a single high-volume center in Japan. Landmark analysis was performed at 30 days to determine short-term and long-term outcomes. Major adverse cardiac events (MACE) were defined as death, myocardial infarction, target vessel revascularization, and requirement for surgical repair. Of 285 patients who experienced coronary perforation, 57 patients (20%) were treated with PCS. The MACE rates were 28% at 30 days, 22% at 1 year, and 38% at 3 years. 30-day MACE was mainly driven by high rates of myocardial infarction (18%) and surgical repair (16%). The rates of target lesion revascularization were 8% and 12% at 1 and 3 years, respectively. Definite stent thrombosis was reported in 2 patients during the follow-up period. In conclusion, despite the relatively high incidence of MACE during early stage of follow-up, implantation of a PCS provides acceptable late clinical outcomes.

Elastin-like recombinamer-covered stents: Towards a fully biocompatible and non-thrombogenic device for cardiovascular diseases

We explored the use of recently developed gels obtained by the catalyst free click reaction of elastin-like recombinamers (ELRs) to fabricate a new class of covered stents. The approach consists in embedding bare metal stents in the ELR gels by injection molding, followed by endothelialization under dynamic pressure and flow conditions in a bioreactor. The mechanical properties of the gels could be easily tuned by choosing the adequate concentration of the ELR components and their biofunctionality could be tailored by inserting specific sequences (RGD and REDV). The ELR-covered stents exhibited mechanical stability under high flow conditions and could undergo crimping and deployment without damage. The presence of RGD in the ELR used to cover the stent supported full endothelialization in less than 2weeks in vitro. Minimal platelet adhesion and fibrin adsorption were detected after exposure to blood, as shown by immunostaining and scanning electron microscopy. These results prove the potential of this approach towards a new and more effective generation of covered stents which exclude the atherosclerotic plaque from the blood stream and have high biocompatibility, physiological hemocompatibility and reduced response of the immune system.

Coronary Perforation Complicating Percutaneous Coronary Intervention - A Case Illustration and Review

Coronary perforation is a potentially fatal complication during percutaneous coronary intervention (PCI). Reports have shown that it occurs in 0.2 to 0.6% of all patients undergoing the procedures. [1-3] Though the frequency of coronary perforation is low, it is a serious and potentially life-threatening situation that warrants prompt recognition and management. Here we illustrate a case of coronary perforation, and review the incidence, causes, clinical sequelae and management of coronary perforation in the current contemporary practice.

Outcomes of covered versus bare-metal balloon-expandable stents for aortoiliac occlusive disease

OBJECTIVE

Randomized trials and retrospective data suggest that covered balloon-expandable (CBE) stents have better short-term patency compared with balloon-expandable bare-metal stents (BMSs) in the treatment of iliac artery disease. This study evaluated midterm outcomes of BMSs vs CBE stents placed in the common iliac artery (CIA) for aortoiliac occlusive disease.

METHODS

All endovascular interventions for symptomatic peripheral arterial occlusive disease performed at a single institution from 2006 to 2012 were reviewed. Patients undergoing stent placement in the CIA segment were included in the analysis. Demographic data, TransAtlantic Inter-Society Consensus (TASC) classification, stent type, patency, and limb reinterventions were compared.

RESULTS

For treatment of de novo distal aorta or CIA stenosis, 254 procedures were performed in 162 patients. BMSs were used in 190 arteries; CBE stents were used in 64 arteries. There was no difference in age, gender, or TASC classification between the two groups. Mean follow-up was 22 ± 16 months. Primary patency, assisted patency, and secondary patency were significantly better in the BMS group. CIAs treated with covered stents were more likely at 1 year or longer to require repeated intervention (hazard ratio, 2.5; 95% confidence interval, 1.2-5.3; P = .009). TASC classification did not predict need for reintervention in either group. Multivariate analysis revealed dual antiplatelet therapy to be the only other factor to affect patency during long-term follow-up.

CONCLUSIONS

In this study, BMSs had significantly better patency compared with CBE stents for treatment of aortoiliac occlusive disease. A randomized trial comparing patency as well as restenosis rates with long-term follow-up is needed to determine if there is any benefit from use of covered stents in the aortoiliac segment.

Self-expanding stents and aortoiliac occlusive disease: a review of the literature

The treatment of symptomatic aortoiliac occlusive disease has shifted from open to endovascular repair. Both short- and long-term outcomes after percutaneous angioplasty and stenting rival those after open repair and justify an endovascular-first approach. In this article, we review the current endovascular treatment strategies in patients with aortoiliac occlusive disease, indications for primary and selective stenting in the iliac artery, and physical properties and future perspectives of self-expanding stents.

A novel carotid covered stent design: in vitro evaluation of performance and influence on the blood flow regime at the carotid artery bifurcation

In the present study, a novel carotid covered stent design has been developed. Prototypes of different geometrical design parameters have been fabricated and their performance has been evaluated in vitro under physiological pulsatile flow condition, utilizing flow visualization (dye injection), and particle image velocimetry techniques. These evaluations include the assessment of emboli prevention capability, side-branch flow preservation, and influence on the branch flow pattern and velocity field. The novel covered stents demonstrated significantly higher emboli prevention capability than the corresponding bare metal stent, while preserving more than 83% of the original flow of the external carotid artery (ECA). Flow in the ECA through these covered stents was uniform without evidence of undesirable flow recirculation and reversed flow that might predispose the vessel wall to post-stenting intimal thickening and atherosclerotic plaque formation. This study demonstrated the potential of these novel covered stent designs for the treatment of carotid atherosclerotic stenosis. However, further computational and in vivo investigations of hemodynamics, biological effects, and mechanical performance of this covered stent design is warranted.

Optical coherence tomographic observations of polytetrafluoroethylene-covered sirolimus-eluting coronary arterial stent

The aim of this study was to evaluate neointimal coverage obtained using a new method of polytetrafluoroethylene-covered stent (PCS) implantation combined with underlying longer sirolimus-eluting stent (SES) implantation using optical coherence tomography. Nine patients were enrolled in this study, including patients with coronary artery perforations, original coronary aneurysms, and acquired coronary aneurysms after drug-eluting stent implantation. All patients were first treated with long SES implantation and then with focal PCS implantation. Postprocedural and follow-up angiographic and optical coherence tomographic examinations were performed in all patients, and intravascular ultrasound was performed in 5 patients. All patients were asymptomatic during follow-up, without recurrent angina. There was no stent-edge or stent-segment binary restenosis. Values of late loss for proximal SES segments, PCS segments, and distal SES segments were similar (0.09, 0.07, and 0.04 mm, respectively, p = 0.8113). The mean neointimal thickness of PCS was less than that of proximal and distal SES. However, no malapposed cross sections or uncovered cross sections were found in PCS segments compared with SES segments (p = 0.0011). In conclusion, the combination of PCS and underlying longer SES implantation can offer better angiographic follow-up results. High-resolution optical coherence tomography provided convincing proof of full neointimal coverage of PCS. This new method of combined PCS and SES implantation may be a better choice compared with direct PCS implantation in certain clinical settings.

DISCOVER: Dutch Iliac Stent trial: COVERed balloon-expandable versus uncovered balloon-expandable stents in the common iliac artery: study protocol for a randomized controlled trial

BACKGROUND

Iliac artery atherosclerotic disease may cause intermittent claudication and critical limb ischemia. It can lead to serious complications such as infection, amputation and even death. Revascularization relieves symptoms and prevents these complications. Historically, open surgical repair, in the form of endarterectomy or bypass, was used. Over the last decade, endovascular repair has become the first choice of treatment for iliac arterial occlusive disease. No definitive consensus has emerged about the best endovascular strategy and which type of stent, if any, to use. However, in more advanced disease, that is, long or multiple stenoses or occlusions, literature is most supportive of primary stenting with a balloon-expandable stent in the common iliac artery (Jongkind V et al., J Vasc Surg 52:1376-1383,2010). Recently, a PTFE-covered balloon-expandable stent (Advanta V12, Atrium Medical Inc., Hudson, NH, USA) has been introduced for the iliac artery. Covering stents with PTFE has been shown to lead to less neo-intimal hyperplasia and this might lower restenosis rates (Dolmatch B et al. J Vasc Interv Radiol 18:527-534,2007, Marin ML et al. J Vasc Interv Radiol 7:651-656,1996, Virmani R et al. J Vasc Interv Radiol 10:445-456,1999). However, only one RCT, of mediocre quality has been published on this stent in the common iliac artery (Mwipatayi BP et al. J Vasc Surg 54:1561-1570,2011, Bekken JA et al. J Vasc Surg 55:1545-1546,2012). Our hypothesis is that covered balloon-expandable stents lead to better results when compared to uncovered balloon-expandable stents.

METHODS/DESIGN

This is a prospective, randomized, controlled, double-blind, multi-center trial. The study population consists of human volunteers aged over 18 years, with symptomatic advanced atherosclerotic disease of the common iliac artery, defined as stenoses longer than 3 cm and occlusions. A total of 174 patients will be included. The control group will undergo endovascular dilatation or revascularization of the common iliac artery, followed by placement of one or more uncovered balloon-expandable stents. The study group will undergo the same treatment, however one or more PTFE-covered balloon-expandable stents will be placed. When necessary, the aorta, external iliac artery, common femoral artery, superficial femoral artery and deep femoral artery will be treated, using the standard treatment. The primary endpoint is absence of binary restenosis rate. Secondary endpoints are reocclusion rate, target-lesion revascularization rate, clinical success, procedural success, hemodynamic success, major amputation rate, complication rate and mortality rate. Main study parameters are age, gender, relevant co-morbidity, and several patient, disease and procedure-related parameters.

TRIAL REGISTRATION

Dutch Trial Register, NTR3381.

Treatment of a coronary artery aneurysm by use of a covered stent graft - a case report

Coronary artery aneurysm is a rare finding at coronary angiography. Most coronary aneurysms remain asymptomatic. There is no consensus on its management; some advocate aggressive approach while others advocate conservative management. A case of coronary artery aneurysm successfully treated by implantation of a polytetrafluoroethylene-covered coronary stent is presented.

Covered stents for coronary perforations: is there enough evidence?

Covered stents have shown discouraging results when tested on saphenous vein grafts and when attempting to prevent restenosis on native coronary arteries. However, covered stents seem to be a unique tool when a coronary artery perforation complicates percutaneous coronary intervention. Because a randomized clinical trial is not likely to be conducted in this bail-out scenario, the data supporting its use come from case reports and small-size retrospective studies. This review summarizes the available evidence supporting the use of covered stents to treat coronary perforations.

Outcomes following treatment of femoropopliteal in-stent restenosis: a single center experience

OBJECTIVES

The aim of this study is to describe a single-center experience with endovascular treatment of femoropopliteal in-stent restenosis (ISR).

BACKGROUND

Femoropopliteal artery stenting is associated with a significant risk of ISR. Data are limited on the optimal treatment strategy and associated outcomes.

METHODS

A single institution retrospective chart review study was performed for patients who underwent endovascular treatment of femoropopliteal ISR from January 2006 to October 2008. Clinical and procedural characteristics, angiographic findings, and 12-month primary and secondary patency rates were analyzed. Univariate analysis was performed to identify predictors of 12-month primary patency.

RESULTS

Twenty-two limbs were treated in 20 patients during the study period. Procedural success was achieved in 21 limbs (95.5%). Laser, balloon angioplasty, and excisional atherectomy were the primary therapy in 52.4%, 33.3%, and 14.3% of the cases, respectively. Adjunctive balloon angioplasty was performed after laser and excisional atherectomy in all cases. The mean length of ISR was 13.2 ± 11.3 cm with a significant proportion of cases (40.9%) having Type IV pattern of ISR. At 12 months, primary and combined primary-assisted and secondary patency rates were 47.6 and 61.9%, respectively. Of the 11 limbs that did not have secondary patency, 6 had mild or no symptoms, and, therefore, repeat intervention was not performed. There was one transmetatarsal amputation during the 12-month follow-up period. In this study, there was no significant predictor of 12-month primary patency.

CONCLUSIONS

Treatment of ISR remains challenging with significant risk of recurrent restenosis. Further research is required to improve long-term patency.

Mechanical Evaluation of Polyvinyl Alcohol Cryogels for Covered Stents

Covered stents could reduce restenosis rates by preventing cellular migration with a physical barrier and may have reduced thrombotic complications if an appropriate material is selected. Previous Dacron™ or poly(tetrafluoroethylene) (PTFE) covered stents have had mixed clinical results in part because they are too thick and too thrombogenic at small diameters. Ideally, the covering should be as thin as a stent strut, mechanically able to expand as much as a stent, and durable enough to withstand deployment. As an alternative to PTFE, thin polyvinyl alcohol (PVA) cryogel membranes were tested for their ability to stretch with uniaxial tension tests and for puncture strength with a modified ASTM method. Additionally, PVA cryogel covered stents were made by coating expanded bare metal stents. These covered stents were then hand-crimped onto a balloon catheter and expanded. PVA cryogel membranes were made as thin as 100 μm—thinner than some stent struts—and stretched to approximately 3.0 times their original diameter (similar to a stent during deployment). PVA cryogel membranes resisted puncture well with an average push-through displacement of 4.77 mm—allowing for safe deployment in vessels of up to 9 mm in diameter. Push-through displacement did not depend on membrane thickness in the range tested—a trait that could reduce stent profile without increased risk of puncture. All the PVA cryogel covered stents tolerated the crimping and expansion process well and there was little to no visible membrane damage. In conclusion, based on the results of these mechanical tests, PVA cryogels are mechanically suitable for covered stent membranes. This work represents a first step toward the creation of a new class of covered stent, which could prevent complications from both restenosis and thrombosis.

Treatment of ruptured ICA during transsphenoidal surgery. Two different endovascular strategies in two cases

Rupture of the internal carotid artery (ICA) during transsphenoidal surgery is a rare but potentially lethal complication. Direct surgical repair of the ICA may be difficult and time-consuming in an acute setting. Urgent endovascular treatments with vascular plug or stent-graft have been the feasible options to date. We desrcibe two cases of iatrogenic rupture of ICA during transsphenoidal surgery. In the first case we occluded the ICA with a vascular plug at the site of tear where cross circulation was adequate. In the second case we had to preserve the ICA with stent-graft since there was no adequate cross circulation. These two strategies are discussed below.

Endovascular graft-stent placement for treatment of traumatic carotid cavernous fistulas

Detachable balloon-based endovascular fistula occlusion is a widely accepted treatment for traumatic carotid cavernous fistulas (CCF). However, more recently coils have been used to obliterate the lesion, especially in case detachable balloon is not available. We failed balloon-assisted coil embolization for CCF because of large fistulas and herniation of coil loops into the parent artery. The authors describe our experiences of balloonexpandable graft-stents to treat CCF, and place emphasis on arterial wall reconstruction. Three traumatic CCF patients were treated using a graft-stent with/without coils, and underwent angiographic follow-up to evaluate the patency of the internal carotid artery (ICA). In all cases, symptoms related to CCF regressed after stent deployment and did not recur during follow-up. Follow-up angiography revealed good patency of the ICA in all patients. Graft-stents should be considered as an alternative means of treating CCF and preserving the parent artery by arterial wall reconstruction especially in patients with a fistula that cannot be successfully occluded with detachable balloons or coils.

Covered Stent Implantation for the Treatment of Direct Carotid-Cavernous Fistula and Its Mid-Term Follow-up

SUMMARY

Carotid-cavernous fistulas are abnormal arteriovenous communications either directly between the internal carotid artery and the cavernous sinus or between the dural branches of the internal and external carotid arteries. These fistulas predominantly present with ocular manifestations and they are treated mainly by endovascular techniques in most cases. A detailed review of the literature allowed us to make a complete analysis of the information available on the topic. We describe a case of a direct carotid-cavernous fistula occluded by endovascular implantation of a covered stent, showing the persistence of results after three years.

Stent graft treatment of cerebrovascular wall defects: intermediate-term clinical and angiographic results

OBJECTIVE

Endovascular stent graft (SG) deployment offers a useful vessel-preserving strategy for vascular wall lesions such as pseudoaneurysms and fistulae. Although deployment of expanded polytetrafluoro-ethylene-covered SGs within the carotid and vertebral arteries is technically feasible, data on long-term efficacy, safety, and patency rate remain sparse.

METHODS

Six patients with traumatic (n = 4), iatrogenic (n = 1), or spontaneous (n = 1) internal carotid and vertebral artery injuries (direct carotid-cavernous fistula, n = 2; pseudoaneurysms, n = 4) were treated with nine balloon-mounted coronary expanded polytetrafluoro-ethylene SGs. Angiographic (mean, 2.3 yr; range, 1.7-4.2 yr) and neurological follow-up (mean, 2.7 yr) was performed for all patients.

RESULTS

Complete angiographic exclusion of the lesion was achieved by the initial procedure in five of the six patients; one ruptured cavernous carotid aneurysm leading to a direct carotid-cavernous fistula showed persistent slow shunting despite tandem deployment of two SGs. All six patients revealed complete and persistent angiographic obliteration at delayed follow-up, with minimal in-stent stenosis (<20%) seen in two instances. Difficulty with SG navigation was encountered in five patients, resulting in one instance of guide catheter-induced intimal dissection. Type I endoleak was observed in five patients, requiring secondary angioplasty in four patients and deployment of an additional tandem SG in three.

CONCLUSION

Technical challenges in current-generation SG deployment include sizing, navigation, positioning, and propensity for endoleak. When managed successfully, stent grafting provides a valuable approach for the treatment of vascular wall defects for which vessel preservation is preferred. Intermediate-term safety is satisfactory, with no delayed complications and minimal in-stent stenosis in follow-up periods of more than 2 years.

Stent-grafts in the treatment of emergent or urgent carotid artery disease: review of 25 cases

PURPOSE

To report the authors' initial experience with carotid artery stent-grafts in a comparatively large patient series for the treatment of acute bleeding and impending rupture or the prevention of distal embolization.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review boards and performed according to HIPPA standards. Twenty-five patients were treated with 27 carotid artery stent-grafts (Gore Viabahn, n = 10; Bard Fluency, n = 9; polytetrafluoroethylene-covered Palmaz, n = 5; and Wallgraft, n = 3). Thirteen stent-grafts were placed in patients with carotid blow-out syndrome (including three patients with carotid-airway fistula), 12 in patients with either pseudoaneurysm (n = 9) or true aneurysm (n = 3), and two in patients with intractable high-grade bare stent restenosis.

RESULTS

The technical success rate was 100% (27 of 27 cases). No acute procedural transient ischemic attacks or strokes occurred. Procedural dissections occurred in two of the 27 cases (7.4%). Short-term complications occurred in three of the 27 cases (11%) (repeat hemorrhage, n = 2; common carotid artery occlusion, n = 1). The overall patient mortality rate was 36% (nine of 25 patients, all with carotid blow-out syndrome). Six-month follow-up in 15 of the 16 living patients demonstrated widely patent stent-grafts. Two patients with pseudoaneurysm also demonstrated patent stents at 18- and 33-month follow-up.

CONCLUSIONS

Stent-grafts may be useful in the treatment of carotid artery bleeding syndrome, aneurysm, and stenosis, with a high procedural success rate in selected cases. The results of mid-term follow-up are encouraging, but results of long-term follow-up must be evaluated in future studies.

Successful trapping of an organized thrombus in a coronary artery aneurysm in myocardial infarction: case report and literature review

A 44-year-old female presented with acute inferior myocardial infarction. Emergency coronary angiography showed an aneurysm of the proximal right coronary artery and an occlusion of the vessel downstream due to a huge organized thrombus. Mechanical fragmentation, glycoprotein IIb/IIIa antagonist, and intracoronary thrombolysis were all tested without success. Finally, the aneurysm was covered with a standard bare metal stent in order to trap the thrombus between the stent and the vessel wall and at least partially in the aneurysm. The strategy was successful, and after 1 week, the blood flow in the right coronary artery was normal; however, the aneurysm remained. After 6 months, there was significant in-stent restenosis of the proximal and mid segments of the right coronary artery but no evidence of the aneurysm. The restenosis was treated with two drug-eluting stents, leading to an excellent result after a further 6 months. The patient was free of symptoms and the left ventricular ejection fraction was within the normal range.

Development of in vivo tissue-engineered autologous tissue-covered stents (biocovered stents)

Biocovered stents, which are stents covered with autologous membranous tissues, were developed by applying a novel concept based on in vivo tissue engineering. Balloon-expandable stents crimped on silicone rods as a mold (diameter: 2 mm) were embedded into dorsal subcutaneous pouches in rabbits. After 1 month, the struts of the stents were fully encapsulated with membranous connective tissues formed around the silicone rods. Upon removing the silicone rod, stents covered with tubular connective tissues, in which the struts were completely impregnated, were obtained as biocovered stents. These tissues were composed mainly of collagen and fibroblasts and had a thickness of less than approximately 200 microm with an excellent high burst strength of approximately 1000 mmHg. The luminal surface of the tissues was extremely flat and smooth. The stents could be mounted on balloon catheters with a hand crimping tool and could be expanded by inflation with little damage to the tissues. It is anticipated that these novel stents may greatly enhance early normal vascular reconstruction with high reliability, thereby reducing the rate of in-stent restenosis.

Covered stent-graft treatment of traumatic internal carotid artery pseudoaneurysms: a review

OBJECTIVE

To review the literature concerning the management with placement of covered stent-grafts of traumatic pseudoaneurysms of the extracranial internal carotid artery (ICA) resulting from penetrating craniocervical injuries or skull base fractures.

METHOD

We have reviewed, from the Medline database, all the published cases in the English literature since 1990 and we have added a new case.

RESULTS

We identified 20 patients with traumatic extracranial ICA pseudoaneurysms due to penetrating craniocervical injuries or skull base fractures who had been treated with covered stent-graft implantation. Many discrepancies have been ascertained regarding the anticoagulation therapy. In 3 patients the ICA was totally occluded in the follow-up period, giving an overall occlusion rate 15%. No serious complication was reported as a result of the endovascular procedure.

CONCLUSION

Preliminary results suggest that placement of stent-grafts is a safe and effective method of treating ICA traumatic pseudoaneurysms resulting from penetrating craniocervical injuries or skull base fractures. The immediate results are satisfactory when the procedure takes place with appropriate anticoagulation therapy. The periprocedural morbidity and mortality and the early patency are also acceptable. A surveillance program with appropriate interventions to manage restenosis may improve the long-term patency.

Exclusion of Atherosclerotic Plaque from the Circulation Using Stent-Grafts: Alternative to Carotid Stenting with a Protection Device?

PURPOSE

To retrospectively assess the feasibility, safety, and clinical mid-term outcome of patients undergoing carotid artery stenting with stent-grafts.

METHODS

Over a 4 year period stent-grafts were used in the endovascular treatment of symptomatic internal carotid artery stenosis in 12 patients (2 women, 10 men, aged 47-83 (mean 64) years). Protection devices were not used. Possible microembolic complications were evaluated by magnetic resonance imaging (MRI) examinations of the brain before and the day after the procedure in all patients. Mean follow-up was 22 months (range 1-42 months), by Doppler ultrasonography and conventional angiography as well as clinical examination.

RESULTS

The technical success rate was 100%. A total of 13 coronary stent-grafts were used. The mean stenosis rate (in terms of diameter) was 85% and the mean length of stent-grafts used was 20.9 mm. The mean diameter to which the stent-grafts were dilated was 4.66 mm. In-hospital complications occurred in 1 patient who suffered a minor femoral access hematoma that did not require transfusion or surgical decompression. Post-stenting diffusion-weighted MRI revealed several ipsilateral silent microemboli in only 1 case, which was completely asymptomatic. Two patients had a major stroke after 2 years of follow-up. Restenosis was found in 2 patients who underwent successful balloon dilatation followed by placement of a self-expandable bare stent within the stent-grafts.

CONCLUSIONS

Stent-grafts may prevent microembolic complications during stenting of atherosclerotic carotid lesions in selected cases, offering immediate exclusion of the atherosclerotic lesion from the circulation by pressing the plaque against the vessel wall. Comparative, randomized studies in larger series of patients are needed with carotid-dedicated stent-graft designs.

Therapeutic Endovascular Treatments for Traumatic Vertebral Artery Injuries

OBJECTIVE

Traumatic vertebral artery injuries pose difficulty in early diagnosis and management because of concomitant neurologic dysfunction and limitations in direct surgical access. The purpose of this report is to review endovascular therapy in patients with traumatic vertebral artery injuries for preservation of the parent artery, and to determine the safety and efficacy of such endovascular therapy.

METHODS

Six patients with traumatic vertebral artery lesions were treated using therapeutic endovascular methods. Endovascular therapy was accomplished by stent insertion or coil embolization or both.

RESULTS

Except one patient who underwent coil embolization of a transected vertebral artery, all dissections and pseudoaneurysms were successfully treated by stent placement or stent-assisted coiling with preservation of parent arteries. No additional surgical procedures for vascular lesions were required. There were no delayed neurologic or vascular complications and no lesions recurred during the follow-up period (mean, 36.7 months).

CONCLUSION

The author's experience demonstrates that endovascular therapy using stents and coils is both feasible and safe in the treatment of traumatic vertebral artery injuries. Endovascular therapy selectively eliminated the vascular abnormality while maintaining the normal patency of the cerebral arteries. Long-term follow-up review of these repairs will be necessary to provide a full evaluation of the safety and efficacy of these devices.

Development of self-expandable covered stents

We newly developed self-expandable covered stents by combining two of our original technologies. Of these, the first is the dip-coating covering method that was developed previously for balloon-expandable stents; the other is the newly developed self-expandable Nitinol stents, namely, Sendai stents. The three types of covered stents with the expansion diameter of 4.5, 5.0, or 6.0 mm thus obtained had a laser-processed microporous elastomeric cover film (pore diameter: 100 microm, interpore distance: 250 microm). Although the film was extremely thin (approximately 15 microm), the film could be expanded without causing any damage, the strut was completely embedded within the film, and the luminal surface of the film was smooth and flat. Mechanical properties such as ideal flexibility to follow the shapes of arteries were almost retained even after covering. As appropriate drugs, the blood-contacting inner and tissue-contacting outer surfaces of the film were differentially coated with argatroban for antithrombogenicity or FK506 for anti-inflammation, respectively. The preliminary in vivo study indicated that the covered stents mounted in the delivery catheter were navigated and placed to appropriate position in the arteries, and permissible neointimal thickening after 1-month implantation was observed similarly in noncovered stents.

Management of pseudoaneurysms in the intracranial segment of the internal carotid artery with covered stents specially designed for use in the intracranial vasculature: technical notes

Vascular diseases like aneurysms, pseudoaneurysms and direct high-flow carotid-cavernous fistulas on the intracranial segment of the internal carotid artery are usually managed through transarterial embolization with detachable coils or balloons. Utility of covered stents has been reported with good results in the treatment of selective cases. But the current generation of covered stents for coronary use is rather stiff and difficult to navigate in tortuous vessels particularly in the intracranial vasculature. Herein, we report on the use and technical respects of balloon-expanded covered stents specially designed for intracranial vasculature in the treatment of two pseudoaneurysms secondary to the successful obliteration of direct CCFs on the intracranial segment of the internal carotid artery. This is the first report of covered stents specially developed for use in intracranial vasculature.

Traumatic carotid cavernous fistula: failure of endovascular treatment with two stent-grafts

SUMMARY

We describe an unconventional endovascular approach in a young patient with large highflow traumatic carotid cavernous fistula that could not be treated by detachable balloon procedure. Two coronary stent-grafts were used to close the large tear of internal carotid artery. After the failure of stenting procedure, the fistula was successfully treated by trapping with two detachable balloons.

Coil embolization of a circumflex coronary aneurysm at the time of percutaneous coronary stenting

Coronary atherosclerotic aneurysm often occurs in association with severe atherosclerotic coronary stenosis. We describe the percutaneous catheter-based approach to coil embolization of a circumflex coronary aneurysm at the time of obtuse marginal branch coronary stent deployment.